U.S. patent application Ser. No. 839,678, filed Mar. 14, 1986, entitled "High Speed Contact Driver For A Circuit Interruption Device", in the name of E. Keith Howell, describes the arrangement of a bridging contact carried by a pair of spaced parallel conductors and arranged between a pair of fixed contacts for rapid separation therefrom when a high current pulse is provided to the opposite ends of the spaced conductors. The spaced-conductor contact driver arrangement rapidly separates the bridging contact from the fixed contacts to interrupt the current in the early stages of the current wave form. The duration of contact separation is limited by heating of the spaced conductors, however.
It has since been determined that the duration of contact separation can be prolonged by means of a magnetic contact driver in combination with the spaced-conductor contact driver. Although simultaneous energization of the spaced-conductor contact driver and the magnetic contact driver increases the rate of acceleration of the bridging contact to allow for circuit interruption in even earlier stages of the current wave form, the magnetic driver may be used alone to provide both high-speed opening and prolonged duration of separation.
The use of a solenoid-driven armature, per se, to separate a bridging contact from a pair of fixed contacts for high speed circuit interruption is described within U.S. Pat. No. 3,407,368, entitled "Current Limiting Circuit Breaker" in the names of E. B. Heft et al., which patent is incorporated herein for purposes of reference. The Heft et al. patent describes a solenoid-drive armature for separating a bridging contact from a pair of fixed contacts within a current-limiting circuit breaker. The tubular armature described therein is arranged coextensive with a magnetic field piece to drive the armature against the bias of a compression type contact spring. The use of the compression contact spring and the coextensive arrangement of the field piece and the armature renders the Heft et al. arrangement too slow for purposes of arcless circuit interruption.
As described within the referenced patent application, for "Arcless" circuit interruption to occur, the bridging contact must be driven out of circuit relation with the current carrying fixed contacts in the shortest possible time duration in order to limit the amount of current that has to be controlled by auxiliary electronic means such as the solid state circuit interrupter described within U.S. patent application Ser. No. 610,947, filed May 16, 1984, entitled "Solid State Current Limiting Interrupter", for example. The magnetic operator of the instant application substantially improves over earlier known devices by accelerating the bridging contact out of electrical connection with the fixed contacts faster than any method previously available.